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Ratiometric Sensing of Intracellular pH Based on Dual Emissive Carbon Dots

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Abstract

Accurate monitoring of intracellular pH in living cells is critical for developing a better understanding of cellular activities. In the current study, label-free carbon dots (p-CDs), which were fabricated using a straightforward one-pot solvothermal treatment of p-phenylenediamine and urea, were employed to create a new ratiometric pH nanosensor. Under single-wavelength excitation (λex = 500 nm), the p-CDs gave dual emission bands at 525 and 623 nm. The fluorescent intensity ratio (I525/I623) was linearly related to pH over the range 4.0 to 8.8 in buffer solutions, indicating that the ratiometric fluorescence nanoprobe may be useful for pH sensing. In pH measurements, the p-CDs also demonstrated outstanding selectivity, reversibility, and photostability. Owing to the advantages outlined above, the nanoprobe was used to monitor the pH of HeLa cells effectively. The label-free CD-based ratiometric nanoprobe features comparatively easy manufacturing and longer excitation and emission wavelengths than the majority of previously reported CD-based ratiometric pH sensors, which is ultimately beneficial for applications in biological imaging.

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Funding

The authors acknowledge financial support from the National Natural Science Foundation of China (Nos. 22177066), Innovation Capability Support Program of Shaanxi (No. 2021KJXX-51), Coconstruction Project of Hanzhong city and Shaanxi University of Technology (SXJ-2103, SXJ-2105) and Open Foundation of Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education (KLSNFM2020007).

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Authors and Affiliations

  1. Shaanxi Key Laboratory of Catalysis, School of Chemistry and Environment Science, Shaanxi University of Technology, 723000, Hanzhong, Shaanxi, China

    Yanli Sun, Qin Wang, Jin Liu, Zuoping Zhao, Lihua Li, Zhifeng Liu, Jiufu Lu, Lingxia Jin & Shengrui Zhang

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  1. Yanli Sun
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  2. Qin Wang
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  3. Jin Liu
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Contributions

Yanli Sun contributed to the methodology, investigations, probe preparation, data collection and curation, and writing-original draft preparation. Jin Liu, Zuoping Zhao, Lihua Li, and Zhifeng Liu contributed to methodology development, data collection, and sample pretreatment. Jiufu Lu and Lingxia Jin contributed to the formal analyses and validation. Qin Wang and Shengrui Zhang performed conceptualization, supervision, writing-reviewing and editing. All authors read and approved the final manuscript.

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Correspondence to Qin Wang or Shengrui Zhang.

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Sun, Y., Wang, Q., Liu, J. et al. Ratiometric Sensing of Intracellular pH Based on Dual Emissive Carbon Dots. J Fluoresc 33, 653–661 (2023). https://doi.org/10.1007/s10895-022-03107-w

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